1. Field of the Invention
The present invention relates to a vehicle control technique featuring multiple sensors, and more particularly to a control technique performed when some of the sensors have developed a fault.
2. Description of the Related Art
Two sensors for providing redundant control inputs are sometimes used in order to enhance the reliability of a control system. When the two sensors operate normally, the control inputs obtained therefrom are substantially equal to each other. However, the two control inputs differ greatly from each other when either sensor develops a fault. An important question is how to perform control in such cases
JPA 9-191501 describes a technique in which control is continued using only one accelerator sensor when one of the two accelerator sensors in an electric vehicle exceeds the upper or lower limit of a normal output range. It is disclosed that when this happens, abrupt variations in torque are limited by a method in which the torque command value presented to a motor control circuit is temporarily delayed or the torque command value is increased substantially rectilinearly.
Such direct control of abrupt variations in torque makes the driver uncomfortable because the resulting torque variations are markedly different from those experienced during normal driving. A need has therefore existed for a technique that would allow a vehicle to remain substantially as maneuverable as during a normal operation even when some accelerator sensors have developed a fault.